ISO 9614-3:2002规定了一种测量垂直于测量表面的声强分量的方法，选择该测量表面是为了封闭声源，从而确定声功率级。 垂直于测量表面的强度分量的表面积分通过将测量表面细分为连续的部分表面，并沿着覆盖部分表面范围的连续路径在每个部分表面上扫描强度探头来近似。测量仪器确定每次扫描期间的平均法向强度分量和平均平方声压。扫描操作可以手动执行，也可以通过机械系统执行。 倍频带或带限加权声功率级由测量的三分之一倍频带值计算得出。该方法适用于任何可以定义物理固定测量表面的源，以及被测源和其他重要外来源产生的声音在时间上固定的源。源由测量表面的选择来定义。该方法适用于满足ISO 9614-3所有相关要求的特定测试环境。 ISO 9614-3规定了附录C中所述的与声功率测定相关的某些辅助程序。结果用于指示测定的质量，以及准确度等级。 如果测定质量不符合ISO 9614-3的要求，则应按照规定的方式修改试验程序。 ISO 9614-3不适用于测量时发现声源声功率为负值的任何频带。 它适用于任何环境中的声源，这些环境随时间的变化既不会使声强测量的精度降低到不可接受的程度，也不会使强度测量探头受到不可接受速度或不稳定的气流的影响。 在某些情况下，会发现试验条件过于不利，无法满足ISO 9614-3的要求。例如，外部噪声水平可能超过测量仪器的动态能力，或在测试过程中变化过大。 在这种情况下，ISO 9614-3中给出的方法不适用于声源声功率级的测定。

ISO 9614-3:2002 specifies a method for measuring the component of sound intensity normal to a measurement surface which is chosen so as to enclose the sound source(s) of which the sound power level is to be determined. Surface integration of the intensity component normal to the measurement surface is approximated by subdividing the measurement surface into contiguous partial surfaces, and scanning the intensity probe over each partial surface along a continuous path which covers the extent of the partial surface. The measurement instrument determines the averaged normal intensity component and averaged squared sound pressure over the duration of each scan. The scanning operation can be performed either manually or by means of a mechanical system. The octave band or band-limited weighted sound power level is calculated from the measured one-third-octave- band values. The method is applicable to any source for which a physically stationary measurement surface can be defined, and on which the sound generated by the source under test and by other significant extraneous sources are stationary in time. The source is defined by the choice of measurement surface. The method is applicable in specific test environments fulfilling all relevant requirements of ISO 9614-3. ISO 9614-3 specifies certain ancillary procedures, described in annex C, to be followed in conjunction with the sound power determination. The results are used to indicate the quality of the determination, and hence the grade of accuracy. If the quality of the determination does not meet the requirements of ISO 9614-3, the test procedure shall be modified in the manner indicated. ISO 9614-3 is not applicable to any frequency band in which the sound power of the source is found to be negative on measurement. It is applicable to sources situated in any environment which is neither so variable over time as to reduce the accuracy of the measurement of sound intensity to an unacceptable degree, nor subjects the intensity measurement probe to gas flows of unacceptable speed or unsteadiness. In some cases it will be found that the test conditions are too adverse to allow the requirements of ISO 9614-3 to be met. For example, extraneous noise levels can exceed the dynamic capability of the measuring instrument or can vary to an excessive degree during the test. In such cases the method given in ISO 9614-3 is not suitable for the determination of the sound power level of the source.